1. Field
The present disclosure relates generally providing platelet containing blood preparation, including platelet-rich-plasma (PRP) that provides numerous benefits and advantages. More specifically, the present disclosure relates to providing platelet-rich plasma with little to no platelet factor 4 (PF4), a most abundant pre-inflammatory protein in PRP which, among other things, reduces inflammation, anti-angiogenesis and anti-osteogenesis and plays a role in soft and hard tissue repair and regeneration in a mammal. Additionally, the present disclosure relates to a method of removing PF4 from platelets containing blood preparations.
2. General Background
Platelet rich plasma (PRP) concentrated from blood, has attracted the attention of researchers as a good source of growth factors. When it is processed from the patient's autologous blood, potential hazard to the patient is low. It is also cost-effective. The use of platelet-rich plasmas (PRPs) has increased significantly over the last decade in the fields of orthopedics, periodontics, maxillofacial surgery, urology, and plastic surgery. The healing potential of PRP is often attributed to the release of multiple growth factors from the highly concentrated platelets. Growth factors released from platelets are believed to include, among other things, platelet-derived growth factor (PDGF), TGF-β, platelet-derived epidermal growth factor (PDEGF), platelet-derived angiogenesis factor (PDAF), and insulin-like growth factors I (IGF-I) and VEGF. These peptide factors alone or in concert with others have mitogenic and chemotactic effects on cells for tissue repair and regeneration.
When PRP is used adjuvant for tissue repair and regeneration, much attention has been paid to the growth factors, such as PDGF, TGF-β and IGF in PRP. Their mitogenic and chemotaxic effect to the mesenchymal stem cell and progenitor cells have been studied extensively in vitro and in vivo. However, when platelets are activated, large amounts of cytokines and chemokines are also released simultaneously with growth factors. Platelets and many of their products are now recognized as playing important roles in the immunoregulation and differentiation of various cell types. During acute vascular injury or chronic disease, activated platelets release a variety of mediators, including three members of the chemokine family, the connective tissue-activating peptide III, RANTES, and the platelet factor 4 (PF41). Among them, the most abundant protein is PF4.
Platelet factor 4 (PF4) is a major secretory protein of activated platelets with molecular weight of 70 kD (1). As a member of the CXC chemokines, PF4 participates in inflammatory responses by attracting monocytes and neutrophils (Xia and Kao 2003). PF4 promotes monocyte survival and induces the differentiation of monocytes into macrophages and is involved in long-term regulatory processes of these cells and might support the differentiation of infiltrating monocytes into macrophages in vivo during intermediate and late stages of an inflammatory process (Scheuerer, Ernst et al. 2000). PF4 possesses characteristic structural features of the pro-inflammatory proteins interleukin-8 and beta-thromboglobulin and has been shown to be chemotactic for neutrophils and monocytes in vivo (Wolpe and Cerami 1989). This similarity of the structure and activities of PF4 to well characterized pro-inflammatory proteins along with the ubiquitous aggregation of platelets at sites of inflammation suggest that PF4 may be an endogenous mediator of inflammation. Thus, it is anticipated that swelling could accompany the administration of PF4 in vivo.
PF4 has been shown to have antiangiogenic properties both in vitro and in vivo (Maione, Gray et al. 1990). Recombinant human PF-4 inhibits blood vessel proliferation in the chicken chorioallantoic membrane assay in a dose-dependent manner. PF-4 inhibits angiogenesis by associating directly with FGF-2, inhibiting its dimerization and blocking FGF-2 binding to endothelial cells. Recombinant human PF-4 has been tested in clinical trials that include Kaposi's sarcoma, colon and kidney carcinomas, and melanoma. In particular, intralesional injection of PF-4 is effective in the treatment of Kaposi's sarcoma.
PF4 also inhibits osteoblast proliferation. It may be used to treat diseases associated with localized changes in bone metabolism in which abnormal osteoblastic cell function/activity contributes to pathogenic bone changes (See U.S. Pat. No. 5,304,542 to Tatakis, entitled “Use Of Platelet Factor 4 To Inhibit Osteoblast Proliferation”).